1. Field of the Invention
The present invention relates to a semiconductor device and a cooling system for cooling the semiconductor device, and more specifically, to a semiconductor device that operates an electrically powered member and a cooling system for cooling the semiconductor device.
2. Description of the Background Art
Regarding vehicles and the like put into practical use in recent years, engine drive is controlled electronically and increasing weight has been put on electronic circuits such as semiconductor devices used for the control. Further, electric vehicles that do not rely on engine drive but use electric power as power sources have also been put into practical use (see Japanese Patent Application Laid-Open No. 2004-166341). Electronic circuits such as semiconductor devices are also used in control of electric vehicles.
In conventional engine driven vehicles, engines are used as heat sources for vehicles' facilities such as air conditioners. Meanwhile, engines are generally not provided in electric vehicles and the like. So, in order to realize temperature control function such as air conditioners in electric vehicles, heat sources such as electric heaters should be prepared additionally.
However, electric heaters generate large power losses. So, power consumption is increased if additionally prepared electric heaters are used, for example. Increase in power consumption reduces electric power available as power sources. resulting in a problem of reduction of a distance to empty in electric vehicles. A problem of reduction of a distance to empty also occurs if the weights of entire vehicles are increased by placement of electric heater units.
Like conventional engine driven vehicles, vehicles using electricity and equipped with engines such as hybrid vehicles are capable of using the engines as heat sources. Meanwhile, these engines should be driven for the purpose of heating up catalysts or actuator units in addition to the purpose of driving the vehicles, making a cause for worsened fuel economy.